102 RESEARCHES ON THE COAGULATION OF THE BLOOD. 
malia, though coagulating soon after death in the heart and 
great venous trunks, remains fluid for days in vessels of 
smaller size, and this under circumstances affording free 
opportunity for the escape of ammonia; and, on the other 
hand, that when a portion of a vessel, either in an amputated 
limb or in a living animal, is treated in a manner calculated 
to destroy its vital properties, the blood coagulates in the 
injured part, but retains its fluidity 7 elsewhere, although there 
is no greater opportunity for the escape of ammonia in the 
one case than in the other. A striking instance of the diffe¬ 
rence between the natural receptacles of the blood and ordi¬ 
nary matter in their relations to the vital fluid happened to 
come under my notice this morning, in an arm which I 
amputated last evening at the shoulder-joint, on account of 
injury inflicted by machinery. On examining the limb, which 
had lain undisturbed since the operation, I saw that the 
axillary vein, which was patulous at the part where it had 
been divided by the knife, contained some blood at a distance 
of about half-an-inch from the open orifice; and having 
squeezed out a few drops, found that it was perfectly fluid, 
but yielded threads of fibrine when the point of a needle was 
drawn through it some minutes after emission. The blood 
had been for upwards of twelve hours freely exposed to the 
air, but being situated in an injured part of a blood-vessel, 
had remained free from coagulation.* 
i( Further, in the opening meeting of last Session I demon¬ 
strated another important principle, viz.—That ordinary solid 
matter, unlike atmospheric air, induces coagulation of blood 
in its vicinity when introduced within the living vessels. 
Having inserted a piece of clean silver wire for a considerable 
distance into one of the veins of an amputated sheep’s foot, 
I slit up the vessel after a short time had elapsed, when I 
exhibited a coagulum extending along the whole length of 
the foreign body, whereas a mere wound of the vein failed to 
induce a clot, except immediately at the spot where the 
injury had been inflicted. It was obvious that the introduc¬ 
tion of the wire could not affect the amount of ammonia in 
the blood ; and from this and manv other facts to which I 
need not here allude, I was led to the opinion, that as regards 
what takes place within the living vessels, the ammonia 
theory might practically be left entirely out of consideration. 
“ What I have to show this evening will, I think, prove that 
even for blood outside the body, the ammonia theory, what- 
* For some of these facts see ‘ Philosophical Transactions,’ for 1855, 
pp. 673, et seq. 
